This message is a summary and an update to a message about Thunderbird that I sent to Mozilla developers on Monday.

Here are the key points. First, Thunderbird and Firefox are interconnected in a few different ways. They are connected through our technical infrastructure. Both use Mozilla build and release systems. This seems arcane but it turns out that “build and release” is a massive component in the development and distribution of complex software projects. They’re connected through the sharing of some pieces of technology. And they share a home in the Mozilla Foundation and the Mozilla Project.

The time has come when it is no longer effective for Thunderbird and Firefox to keep sharing the same technical infrastructure. Firefox and Thunderbird have diverging needs. Firefox needs to move at the speed of the Web, and needs to bring the things we love about the Web into the world of mobile, social, data and the cloud. That’s a fiercely competitive setting with high consequences. We need to be laser-focused if we want to move these parts of online life towards the traits of individual user centrality and control, openness, interoperability and a level playing field. Thunderbird is a valuable and respected open source project, with different parameters. In my message on Monday I noted that planning for the future should be based on the need to plan for a future where the technical infrastructure of Firefox and Thunderbird are separate.

I’ve seen some characterize this as Mozilla “dropping” Thunderbird. This is not accurate. We are going to disentangle the technical infrastructure. We are going to assist the Thunderbird community. This includes working with organizations that want to invest in Thunderbird, several of which have stepped forward already. Mozilla Foundation will serve as a fiscal sponsor for Thunderbird donations during this time.

I also noted that we should look at whether Mozilla remains the best organizational and legal home for Thunderbird. This is a separate question from the technical infrastructure. This question is much more wide open. I don’t know what the answer will be. It could be that Mozilla remains the best home, based on history, affiliation and shared community. It could also be that a home geared to open source projects of Thunderbird’s size and scope is better suited. I can imagine either being the case. We have decided to separate the technical infrastructure and to explore what is best for Thunderbird and for the Mozilla project as a whole.

These discussions are at a very early stage. Finding the right solution requires some effort. This is Mozilla focusing on a more forward looking path, one aimed at longer term stability rather than continuing the status quo.